A type of power semiconductor device module includes an injection molded plastic housing. The injection molded housing has a frame-shape that extends around a metal baseplate so that the housing and the metal baseplate together form a tray-shaped recess. The metal baseplate forms the bottom of the tray. Disposed on the top of the metal baseplate in the bottom of the tray is a DMB (Direct Metal Bonded) and semiconductor device assembly. The DMB and semiconductor device assembly includes a DMB structure. The DMB structure is a multi-layer structure that includes an insulative but heat-conductive center ceramic substrate layer. A planar bottom direct metal bonded metal layer is bonded to the bottom surface of the ceramic layer, and a planar top direct metal bonded metal layer is bonded to the top surface of the ceramic layer. The top direct metal bonded metal layer is patterned into a plurality of islands of metal. Discrete semiconductor device dice are surface mounted to the various islands on the top the DMB structure in a way consistent with an overall power device circuit to be realized by the module. The various discrete semiconductor device dice and various portions of the DMB structure are interconnected by bonding wires, both to each other, as well as to external connection terminals of the module, such that the overall wire bonded assembly is a desired power device circuit. The assembly within the tray is then covered over with a layer of soft silicone gel or other soft encapsulant. A plastic cap is then fixed over the top of the tray. Such power semiconductor device modules see widespread use in the power semiconductor device industry. Ways of improving such power semiconductor device modules are sought.